Well, that's strange. It works fine on our side. Can you please do another try, but this time don't change anything in our software - don't change the LO frequency or the sampling rate either and don't do anything with the ENSM. Measure and tell us the exact frequency of the peak for:

As mentioned early, we are using our own custom board with filters and matching networks tuned for the frequency range of 70MHz to 512MHz. So, I just change the LO frequency to 300MHz in init structure.